PRGM mode doesn't work on HP-25


Hello all,

I have this HP-25 that is in very good cosmetic condition and as all the keys working, but there are some strange problems with it.

1 - The STO and RCL keys work, but I cannot recall what I've saves in the registers, I always get an 0
2 - In PRGM mode, I can write my program, and it shows the steps like it should, but when I try to RUN it ... nothing, I always get an 0

Can anybody help me fixing it?



Hi Jorge,
I'm assuming you realize that the HP25 is volatile, and if turned off, all registers and program memory are lost.

Otherwise, it sounds like a power continuity problem causing data to be lost, most likely the battery contacts...which need to be scrupulously clean in a woodstock. Also be sure the all contact points within the battery pack are clean also. And be sure not to connect the calculator to the AC adapter unless you're positive you have a good battery pack with good contact installed (this could over-voltage the machine). I personally never connect my machine to an AC adapter, period. With my 29C I sometimes have to "seat" the battery pack by pressing it in the direction as if to remove it, but stopping short of actually removing it.
Best Regards, Hal



Thank you for your answer.

I've tried to clean the contacts and even that way (with the calculator plugged to the AC charger or not). the problems remain.


Enter a few program keystrokes. If, upon review the operations change back to 13 00, the RAM IC has failed. Unfortunately, the only replacement source is from another 25.



yeah, it always keeps showing the 13 00 in program mode no matter whatever I write.
So this must be it's problem :(
Can I find the replacement part you told about in any other unit? For instance a cheaper HP-21 ?


Unfortunately the HP-25 is generally the least expensive calculator that has the appropriate RAM chip. I have just posted to the articles forum a
comparison of Woodstock RAM chips.

Possibly Related Threads...
Thread Author Replies Views Last Post
  Strange HP 25 Problem (Repair) Onur Ilkorur 5 547 12-06-2013, 05:13 PM
Last Post: Onur Ilkorur
  Integration question and "RPN" mode comment Craig Thomas 16 1,295 12-05-2013, 02:32 AM
Last Post: Nick_S
  HP-25 Wayne Selway 1 252 11-22-2013, 12:58 PM
Last Post: Michael de Estrada
  HP Prime: Recommendation for future RPN Program Mode BruceTTT 3 371 11-13-2013, 10:03 PM
Last Post: BruceTTT
  emu48 - copy stack doesn't work (as expected) Thomas Radtke 2 468 11-11-2013, 02:19 PM
Last Post: Thomas Radtke
  Another Prime mystery - templates don't work anymore Michael de Estrada 2 352 11-02-2013, 11:34 AM
Last Post: Michael de Estrada
  Program to change entry mode on Prime Michael de Estrada 3 377 10-28-2013, 10:13 AM
Last Post: Han
  Loading .prgm files to the Prime Thomas Chrapkiewicz 8 654 10-25-2013, 09:34 AM
Last Post: Eddie W. Shore
  Prime: Exam mode (possible duplicate after funny response first time) Paul Townsend (UK) 1 262 10-24-2013, 03:09 PM
Last Post: Tim Wessman
  Does RPN entry mode cause the Prime keyboard to lock up ? Michael de Estrada 14 953 10-22-2013, 06:27 PM
Last Post: John Colvin

Forum Jump: